Focus-less inspection apparatus and method

ABSTRACT

The present disclosure proposes an inspection apparatus. The inspection apparatus may include: a structured-light source configured to sequentially radiate a plurality of structured lights having one phase range; a lens configured to adjust, for each of the plurality of structured lights, optical paths of light beams corresponding to phases of the phase range such that a light beam corresponding to one phase of the phase range arrives at each point of a partial region on an object; an image sensor configured to capture a plurality of reflected lights generated by the structured lights being reflected from the partial region; and a processor configured to acquire a light quantity value of the reflected lights; and derive an angle of the surface by deriving phase values of the reflected lights based on the light quantity value for the reflected lights.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of U.S. patentapplication Ser. No. 16/653,291, filed Oct. 15, 2019 (now pending), thedisclosure of which is herein incorporated by reference in its entirety.The U.S. patent application Ser. No. 16/653,291 claims the benefit ofpriority from Korean Patent Application No. 10-2018-0122354 filed onOct. 15, 2018, and Korean Patent Application No. 10-2018-0159872 filedon Dec. 12, 2018, the entire contents of which are incorporated hereinby reference.

TECHNICAL FIELD

The present disclosure relates to a focus-less inspection apparatus andmethod.

BACKGROUND

Various tests are conducted in a semiconductor manufacturing process inorder to determine whether various treatments, processes and the likefor semiconductors have been properly performed. For example, aninspection may be performed as to, for example, whether a component suchas a die installed on a semiconductor substrate is disposed at aposition where the component is supposed to be disposed on thesemiconductor substrate.

In particular, in a die mounted on a semiconductor substrate, aninspection may be performed as to whether or not there is a tilt betweenthe mounted die and the substrate. Generally, in the state in whichsolder or a solder ball is applied on a substrate, a die may be mountedon top of the solder or solder ball. In this operation, the lowersurface of the die should be mounted parallel to the reference plane ofthe semiconductor substrate, but may be mounted such that the die istilted at a predetermined angle or more with respect to thesemiconductor substrate due to various factors (e.g., the applicationstale of the solder or solder ball). Since the tilt may cause a defectin the semiconductor device, it is necessary to be able to determine inthe process of inspecting the semiconductor whether the die is tiltedand, if tilted, whether the die is tilted at a predetermined angle ormore.

In addition, an inspection of a surface of any object may be performedirrespective of mounting on a substrate. In this inspection process, itis necessary to determine the angle of the unevenness of the surface ofthe object. The surface of the object may have large and smallirregularities depending on the shape of the object. Theseirregularities may be caused by manufacturing defects, or may beintentionally formed by design. It is necessary to measure the angle ofthe surface of the object with respect to a reference plane.

In order to perform an inspection for tilt or the like, athree-dimensional inspection apparatus for irradiating the semiconductordie with three-dimensional illumination may be utilized. A method ofmeasuring the degree of tilt of an object using an imaging position of areflected light from the object has been used. This method measures thedegree of tilt of an object using a difference between the imagingposition of a reflected light reflected from a non-tilted object and theimaging position of a reflected light reflected from a tilted object.However, this method has a problem in that a large space is required formeasuring a changed imaging position of the reflected light because thereflection angle greatly changes even if the object is tilted by only asmall angle. This problem has made it difficult to miniaturizeinspection equipment.

In addition, a method has been conventionally used in which a structuredlight is radiated to an object, a diffraction pattern is formed by thestructured light in the air at a predetermined distance from the object,and the degree of tilt of the object is measured through a phase changeof the diffraction pattern, which is caused as the object is tilted. Inthis method, as the object is tilted, the range of a measureddiffraction pattern changes due to the change of the position of acamera aperture, and the tilt angle of the object may be derived usingthe phase change of the diffraction pattern caused thereby. However, inthis method, there is a problem in that a lot of noise is generatedbecause the diffraction pattern is physically formed in the air.

SUMMARY

The present disclosure has been made to solve the problems describedabove, and provides a technique for measuring a degree of tilt or anobject mounted on a substrate or an angle of a surface of the objectusing a reflected light quantity from the object.

As an aspect of the present disclosure, an inspection apparatus isproposed. An inspection apparatus according to an aspect of the presentdisclosure may include: a structured-light source configured tosequentially radiate a plurality of structured lights having one phaserange; at least one lens configured to adjust, for each of the pluralityof structured lights, optical paths of light beams corresponding tophases of the phase range such that a light beam corresponding to onephase of the phase range arrives at each point of a partial region on asurface of an object; an image sensor configured to capture a pluralityof reflected lights generated by each of the plurality of structuredlights being reflected from the partial region; and a processorelectrically connected to the structured-light source, the at least onelens and the image sensor, the processor being configured to: acquire alight quantity value of each of the plurality of reflected lights fromthe image sensor; and derive an angle of the surface of the object withrespect to a reference plane by deriving phase values of the pluralityof reflected lights based on the light quantity value for each of theplurality of reflected lights.

In an embodiment, the inspection apparatus may further include: amemory, which is electrically connected to the processor, configured tostore reference information indicating a relation between the angle ofthe surface of the object and the phase values of the plurality ofreflected lights.

In an embodiment, the processor may be configured to derive the angle ofthe surface of the object based on the phase values of the plurality ofreflected lights and the reference information acquired from the memory.

In an embodiment, the phase range may not be an integer multiple of aperiod of the plurality of structured lights.

In an embodiment, the phase range may be greater than a phase rangecorresponding to a half-period of the plurality of structured lights andsmaller than a phase range corresponding to the period of the pluralityof structured lights.

In an embodiment, the inspection apparatus may further include: a firstbeam splitter disposed on a first axis perpendicular to the referenceplane, and configured to adjust an optical path of each of the pluralityof structured lights radiated from the structured-light source such thateach of the plurality of structured lights is directed toward thesurface of the object, wherein the image sensor is disposed on the firstaxis.

In an embodiment, the inspection apparatus may further include: a firstdiaphragm configured to pass each of the plurality of structured lightsradiated from the structured-light source toward the first beamsplitter; and a second diaphragm configured to pass each of theplurality of reflected lights reflected from the surface of the objecttoward the image sensor, wherein the light quantity value is determinedbased on a light quantity of each of the plurality of reflected lightspassing through the second diaphragm and being captured by the imagesensor, each of the plurality of reflected lights being generated by theplurality of structured lights passing through the first diaphragm andbeing reflected from the surface of the object, wherein the lightquantity of each of the plurality of reflected lights passing throughthe second diaphragm changes depending on the angle of the surface ofthe object.

In an embodiment, a light beam having an average light quantity of thestructured light and corresponding to the phase range may arrive at eachpoint of the partial region on the surface of the object.

In an embodiment, each of the plurality of structured lights may begenerated by phase-shifting one structured light by a predeterminedphase interval.

In an embodiment, the structured-light source may include: a lightsource configured to radiate an illumination light; a diffusion plateconfigured to diffuse the illumination light; a second beam splitterconfigured to transmit a first polarized light of the diffusedillumination light and to reflect a second polarized light of thediffused illumination light; and a pattern generator configured toreflect a part of the transmitted first polarized light as a firstpolarized light and to reflect an other part of the transmitted firstpolarized light as a second polarized light by converting the other partof the transmitted first polarized light into the second polarizedlight, wherein the second beam splitter transmits the reflected firstpolarized light from the pattern generator and reflects the convertedsecond polarized light from the pattern generator toward the first beamsplitter so as to generate the plurality of structured lights.

In an embodiment, the pattern generator may be a Liquid Crystal onSilicon (LCoS).

In an embodiment, each of the plurality of structured lights may have apattern oriented in a first direction or a pattern oriented in a seconddirection perpendicular to the first direction.

As an aspect of the present disclosure, an inspection method performedby an inspection apparatus is proposed. An inspection method accordingto an aspect of the present disclosure may include: sequentiallyradiating, by a structured-light source of the inspection apparatus,each of a plurality of structured lights having one phase range;adjusting for each of the plurality of structured lights, by at leastone lens of the inspection apparatus, optical paths of light beamscorresponding to phases of the phase range such that a light beamcorresponding to one phase of the phase range arrives at each point of apartial region on a surface of an object; capturing, by an image sensorof the inspection apparatus, a plurality of reflected lights generatedby each of the plurality of structured lights being reflected from thepartial region; acquiring, by a processor of the inspection apparatus, alight quantity value of each of the plurality of reflected lights fromthe image sensor; deriving, by the processor, a phase value of each ofthe plurality of reflected lights based on the light quantity value;acquiring, by the processor, reference information indicating a relationbetween an angle of the surface of the object with respect to areference plane and the phase value of each of the plurality ofreflected lights; and deriving, by the processor, the angle of thesurface of the object based on the phase value of each of the pluralityof reflected lights and the reference information.

In an embodiment, the phase range may not be an integer multiple of aperiod of the plurality of structured lights.

In an embodiment, the inspection apparatus may further comprise: a firstdiaphragm configured to pass each of the plurality of structured lightsradiated from the structured-light source toward a first beam splitter;and a second diaphragm configured to pass each of the plurality ofreflected lights reflected from the surface of the object toward theimage sensor, wherein the light quantity value is determined based on alight quantity of each of the plurality of reflected lights passingthrough the second diaphragm and being captured by the image sensor,each of the plurality of reflected lights being generated by theplurality of structured lights passing through the first diaphragm andbeing reflected from the surface of the object, wherein the lightquantity of each of the plurality of reflected lights passing throughthe second diaphragm changes depending on the angle of the surface ofthe object.

In an embodiment, a light beam having an average light quantity of thestructured light and corresponding to the phase range may arrive at eachpoint of the partial region on the surface of the object.

In an embodiment, each of the plurality of structured lights may begenerated by phase-shifting one structured light by a predeterminedphase interval.

As an aspect of the present disclosure, a non-transitorycomputer-readable storage medium that stores a program is proposed. In astorage medium according to an aspect of the present disclosure, theprogram may include executable commands that, when executed by aprocessor, cause the processor to perform: acquiring a light quantityvalue of each of a plurality of reflected lights generated by each of aplurality of structured lights being reflected from a partial region ofa surface of an object, wherein the plurality of structured lightshaving a predetermined phase range are radiated such that a light beamcorresponding to one phase of the phase range arrives at each point ofthe partial region on the surface of the object; deriving a phase valueof each of the plurality of reflected lights based on the light quantityvalue; acquiring reference information indicating a relation between anangle of the surface of the object with respect to a reference plane andthe phase value of each of the plurality of reflected lights; andderiving the angle of the surface of the object based on the phase valueof each of the plurality of reflected lights and the referenceinformation.

In an embodiment, a light beam having an average light quantity of thestructured light and corresponding to the phase range may arrive at eachpoint of the partial region on the surface of the object.

An inspection apparatus according to various embodiments of the presentdisclosure is able to efficiently measure the degree of tilt of anobject with respect to a substrate or the angle of the surface of theobject using the light quantity of a reflected light from the object.

An inspection apparatus according to various embodiments of the presentdisclosure does not observe the amount of change in the position atwhich the reflected light, reflected from an object, is imaged. Thus, itis not necessary to increase the size of the apparatus in order tomeasure the degree of tilt of the object or the angle of the surface ofthe object.

An inspection apparatus according to various embodiments of the presentdisclosure does not use a diffraction pattern formed in the air in frontof an object. Thus, the inspection apparatus is able to be relativelyrobust against noise in measuring the degree of tilt of the object orthe angle of the surface of the object.

BRIEF DESCRIPTION OF DRAWINGS

The above and other aspects, features and advantages of the presentdisclosure will be more apparent from the following detailed descriptiontaken in conjunction with the accompanying drawings, in which:

FIG. 1 is a block diagram of an inspection apparatus according tovarious embodiments of the present disclosure.

FIG. 2 illustrates an embodiment of a process of operating theinspection apparatus according to the present disclosure.

FIG. 3 illustrates a process in which structured light is radiated ontothe object according to an embodiment of the present disclosure.

FIG. 4 illustrates a process in which reflected light passes through asecond diaphragm according to an embodiment of the present disclosure.

FIG. 5 illustrates a process in which reflected light passes through thesecond diaphragm according to an embodiment of the present disclosure.

FIG. 6 illustrates the view of a plurality of structured lights in afirst diaphragm 160 radiated from the structured-light source 130according to an embodiment of the present disclosure.

FIG. 7 is a table illustrating reference information according to anembodiment of the present disclosure.

FIG. 8 shows the directions of patterns of structured light according toan embodiment of the present disclosure.

FIG. 9 illustrates the configuration of the structured-light source 130according to an embodiment of the present disclosure.

FIG. 10 is a flowchart illustrating an embodiment of an inspectionmethod that may be performed using an inspection apparatus 10 accordingto the present disclosure.

DETAILED DESCRIPTION

Various embodiments described herein are illustrated for the purpose ofclarifying the technical idea of the present disclosure, and are notintended to limit the present disclosure to any specific embodiment. Thetechnical idea of the present disclosure includes various modifications,equivalents, alternatives and embodiments selectively combined from allor part of each embodiment described in the present document. Further,the scope of the technical idea of the present disclosure is not limitedto the various embodiments described below, and the detailed descriptionthereof.

In the present disclosure, terms including technical or scientificterms, may have a meaning that is generally understood by thoseordinarily skilled in the art to which this disclosure belongs, unlessotherwise defined.

In the present disclosure, the expressions “A includes B”, “A mayinclude B”, “A is provided with B”, “A may be provided with B”, “A hasB”, “A may have B”, and the like, mean that corresponding features(e.g., functions, operations, or components, etc.) are present, but donot exclude the presence of other additional features. That is, suchexpressions should be understood as open-ended terms that include thepossibility of including other embodiments.

In the present disclosure, the singular of an expression may include themeaning of the plural of the expression, unless the context dictatesotherwise, and the same applies to singular forms of expressions as setforth in the claims.

In the present disclosure, the expressions “1st”, “2nd”, “first”,“second”, and the like are used to distinguish one object from anotherin referring to plural identical objects unless otherwise indicated inthe context, and do not limit the order or importance of objects.

In the present disclosure, the expressions “A, B and C,” “A, B or C,”“A, B and/or C,” “at least one of A, B, and C,” “at least one of A, B,and C,” “at least one of A, B, and/or C,” and the like may mean eachlisted item or any possible combination of the listed items. Forexample, the expression “at least one of A or B” may mean all of (1) atleast one A, (2) at least one B, and (3) at least one A and at least oneB.

In the present disclosure, the expression “based on . . . ” is used todescribe one or more factors that affect the action or operation of adecision or determination, described in a phrase or sentence in whichthe expression is contained, and does not exclude additional factorsthat influence the action or operation of the corresponding decisions ordetermination.

In the present disclosure, the expression that a component (e.g., afirst component) is “connected” or “coupled” to another component (e.g.,a second component) may mean that the first component is connected orcoupled to the second component not only directly, but also via anothernew component (e.g., a third component).

In the present disclosure, the expression “configured to . . . ” isintended to encompass, depending on the context, the meanings of “set to. . . ,” “being capable of . . . ,” “altered to . . . ,” “made to . . .,” and “able to . . . ,” and the like. The corresponding expression isnot limited to the meaning “specifically designed in hardware”. Forexample, a processor configured to perform a specific operation may meana generic-purpose processor that can perform the specific operation byexecuting software.

In order to illustrate various embodiments of the present disclosure, anorthogonal coordinate system having X, Y, and Z axes orthogonal to eachother may be defined. The expressions such as “X-axis direction,”“Y-axis direction”, “Z-axis direction”, and the like of the orthogonalcoordinate system used in the present disclosure may mean bothdirections in which each axis of the orthogonal coordinate systemextends unless specifically defined otherwise. The plus (+) signprefixed to a term indicating each axis direction may mean the positivedirection, which is one of both directions extending in thecorresponding axis direction, and the minus (−) sign prefixed to a termindicating each axis direction may mean the negative direction, which isthe other one of the both directions extending in the corresponding axisdirection.

In the present disclosure, a substrate is a plate or a container wherean element such as a semiconductor chip is mounted, and may serve as aninter-device connection path for electrical signals. The substrate maybe used for producing an integrated circuit or the like, and may be madeof a material such as silicon. For example, the substrate may be aPrinted Circuit Board (PCB), and may be referred to as a wafer or thelike in some embodiments.

Various embodiments of the present disclosure will now be described withreference to the accompanying drawings. In the accompanying drawings andthe descriptions of the drawings, substantially equivalent elements maybe given the same reference numerals. In the following description ofthe various embodiments, a description of the same or correspondingcomponents may be omitted. However, this does not mean that thecomponents are not included in the embodiment.

FIG. 1 is a block diagram of an inspection apparatus 10 according tovarious embodiments of the present disclosure. The inspection apparatus10 according to various embodiments of the present disclosure is able tomeasure the degree of tilt of an object (e.g., a component) mounted on asubstrate with respect to the substrate surface or the angle of thesurface of the object with respect to a reference plane. For convenienceof explanation in the present disclosure, it is assumed that theinspection apparatus measures the angle of the surface of the object.However, the inspection apparatus may also be used for measuring thedegree of tilt of a component mounted on a substrate. Here, thereference plane may be a virtual plane serving as a reference inmeasuring the angle of unevenness of the surface of an object or thelike. The angle of the surface of the object may mean the angle of atangent at a point on the surface of the object with respect to thereference plane. In an embodiment, the inspection apparatus 10 mayderive the angle of the surface of the object based on the lightquantity of reflected light reflected from the surface of the object.

The inspection apparatus 10 according to various embodiments of thepresent disclosure may include a structured-light source 130, a lens set190, an image sensor 140, a processor 110, and/or a memory 120. In anembodiment, at least one of these components of the inspection apparatus10 may be omitted, or another component may be added to the inspectionapparatus 10. Additionally or alternatively, some of the components maybe integrated or implemented as a single entity or multiple entities.

At least some of the components inside or outside the inspectionapparatus 10 are connected to each other via a bus, a General-PurposeInput/Output (GPIO), a Serial Peripheral Interface (SPI), or a MobileIndustry Processor Interface (MIPI) so as to exchange data and/orsignals.

The structured-light source 130 may sequentially radiate a plurality ofstructured lights having one phase range. Structured light may be lightadded with a characteristic (pattern) unique to the light for objectrecognition or the like. In an embodiment, the structured light may havea pattern in which brightness progressively changes. In an embodiment,the pattern of the structured light may have a constant period. In anembodiment, the pattern of the structured light may be in the form of asine wave. The pattern of the structured light may be formed by, forexample, the brightness of light. In an embodiment, the structured-lightsource 130 may include a plurality of point light sources. The pluralityof point light sources may have different brightnesses depending on thepositions of the plurality of point light sources such that thecorresponding structured light has a pattern. In an embodiment, thestructured light may have a pattern corresponding to a predeterminedphase range. In an embodiment, a plurality of structured lights may begenerated by phase-shifting one structured light by a predeterminedphase interval.

The lens set 190 may adjust the optical paths of the plurality ofstructured lights. The lens set 190 may include at least one lens. Thelens set 190 may adjust an optical path of the light beam correspondingto each phase such that the light beam corresponding to one phase of thestructured light arrives at each point of a partial region on thesurface of the object 3. Here, the partial region may be referred to asa Field Of View (FOV). The light beam corresponding to one phase of thepattern of the structured light may be uniformly radiated to the wholeregion of the FOV. In this way, the lens set 190 may adjust the opticalpath of each of the plurality of structured lights. According to anembodiment, the inspection apparatus 10 may further include a first beamsplitter 150 to be described later, and the first beam splitter 150 mayadjust the optical path of each of the plurality of structured lightstogether with the lens set 190 as described above.

The image sensor 140 may capture a plurality of reflected lightsgenerated when each of the plurality of structured lights is reflectedfrom the partial region on the surface of the object 3 described above.The image of the above-mentioned partial region (the FOV) may be pickedup by the image sensor. One point of the FOV may be imaged at one point(pixel) of the image sensor. According to an embodiment, the imagesensor 140 may be implemented by a Charge Coupled Device (CCD) or aComplementary Metal-Oxide-Semiconductor (CMOS).

The processor 110 may drive software (e.g., a program) so as to controlat least one component of the inspection apparatus 10 connected to theprocessor 110. The processor 110 may also perform various operations,processes, data generation, processing, and the like, which are relatedto the present disclosure. The processor 110 may also load data or thelike from memory 120 or store the data in the memory 120.

The processor 110 may acquire a light quantity value of each of theplurality of reflected lights from the image sensor 140. The processor110 may obtain the light quantity value of a reflected light reflectedfrom the surface of the object 3 by any one structured light among theplurality of structured lights that have been generated by thephase-shift described above. In the same manner, the processor 110 mayacquire the light quantity value of each of the plurality of reflectedlights generated by the plurality of structured lights. The lightquantity values of the reflected lights obtained by the processor 110from the image sensor 140 may be affected by the light quantity passingthrough the first diaphragm 160 and the second diaphragm 170, which willbe described later. The processor 110 may derive the angle of thesurface of the object 3 based on the light quantity value for each ofthe plurality of reflected lights.

In an embodiment, the inspection apparatus 10 may further include amemory 120. The memory 120 may store various data. The data stored inthe memory 120 may be acquired, processed, or used by at least onecomponent of the inspection apparatus 10, and may include software(e.g., a program). The memory 120 may include a volatile memory and/or anon-volatile memory. The memory 120 may store reference information. Thereference information may indicate a relation between the angle of thesurface of the object 3 and the phase values of the plurality ofreflected lights.

In an embodiment, the processor 110 may derive the phase value of eachof the plurality of reflected lights based on the light quantity valueof each of the plurality of reflected lights acquired from the imagesensor 140. The processor 110 may derive the angle of the surface of theobject 3 based on the derived phase value of each of the reflectedlights and the reference information acquired from the memory 120.

In the present disclosure, a program is software stored in the memory120 and may include an operating system for controlling the resources ofthe inspection apparatus 10, an application, and/or a middleware thatprovides various functions to the application, so that the applicationcan utilize the resources of the inspection apparatus.

FIG. 2 illustrates an embodiment of a process of operating theinspection apparatus 10 according to the present disclosure. Asdescribed above, the inspection apparatus 10 according to variousembodiments of the present disclosure may measure the angle of thesurface of an object with respect to a reference plane.

Specifically, the structured-light source 130 of the inspectionapparatus 10 may radiate a structured light having a phase range. In anembodiment, the structured-light source 130 may sequentially radiate aplurality of structured lights that are generated by phase-shifting onestructured light by a predetermined phase interval.

The structured light may be radiated to an object 3 via the lens set 190and/or the first beam splitter 150. The lens set 190 may include atleast one lens 161 and/or 171. The structured light may be transmittedto the first beam splitter 150 via the lens in front of thestructured-light source 130 and the structured light reflected by thefirst beam splitter 150 may be radiated to the object 3 through the lens161. In some embodiments, the lens in front of the light source may beomitted. The structured light radiated from the structured-light source130 may pass through the first diaphragm 160 upon being incident on thefirst beam splitter 150. The first beam splitter 150 may adjust theoptical path such that each of the plurality of structured lightsradiated from the structured-light source 130 is directed to the object3.

In an embodiment, the structured light may be radiated on the object 3such that a light beam corresponding to one phase of the structuredlight arrives at each point of a partial region on the object 3. Thestructured light may have a pattern according to a predetermined period,and each light beam forming the pattern of the structured light may havea phase. At least one lens of the inspection apparatus 10 may beconfigured to adjust the optical path of the structured light such thateach light beam corresponding to one phase of the structured light isuniformly radiated to the above-described partial region on the object3, rather than being concentrated at any one point on the object 3. Thatis, the light beam corresponding to one phase within the above-describedphase range may be divided into each point of the partial region on theobject 3 and incident thereon. Similarly, the at least one lens mayadjust the optical path of the structured light such that the lightbeams corresponding to respective phases within the above-describedphase range of the structured light are uniformly radiated to thepartial region on the object 3 described above. Since the light beams ofrespective phases of the structured light are radiated to the object inthis form, a light beam having a light quantity corresponding to theaverage light quantity of the structured light may be radiated all overthe above-described partial region on the object.

Each of the plurality of structured lights may be reflected from thepartial region on the object 3 to generate each of a plurality ofreflected lights. Each of the plurality of reflected lights may passthrough the lens 161 and the first beam splitter 150. Each of theplurality of reflected lights having passed through the first beamsplitter 150 may be input to the image sensor 140 via the seconddiaphragm 170 and the lens 171. The image sensor 140 of the inspectionapparatus 10 may capture each of the plurality of reflected lights.

The processor 110 of the inspection apparatus 10 may acquire a lightquantity value of each of the plurality of reflected lights from theimage sensor 140. The inspection apparatus 10 may derive the angle ofthe surface of the object 3 based on the acquired light quantity value.In this operation, each of the reflected lights reflected from thesurface of the object 3 may have an average light quantity of structuredlight according to the above-mentioned phase range. When the surface ofthe object 3 is tilted with respect to the reference plane, only aportion of the reflected light reflected from the surface of the object3 passes through the second diaphragm 170 to be input into the imagesensor 140. Therefore, the image sensor 140 may be able to capture onlya portion of the reflected light. The portion of the reflected lightcaptured may correspond to a partial phase range of the above-mentionedphase range of the corresponding structured light. As a result, thelight quantity input into the image sensor 140 through the seconddiaphragm 170 may vary depending on the angle of the surface of theobject 3. The inspection apparatus 10 may derive the angle of thesurface of the object 3 using a change in the light quantity.

In an embodiment, the inspection apparatus 10 may measure the lightquantity for each of the plurality of reflected lights so as to derivethe angle of the surface of the object 3. In an embodiment, theinspection apparatus 10 may derive the angle of the surface of theobject 3 based on the obtained light quantity value and the referenceinformation indicating the relation between light quantity values andangles of a surface of an object. In an embodiment, the lenses 161 and171, the first beam splitter 150, the second diaphragm 170 and/or theimage sensor 140 may be disposed on a first axis perpendicular to thereference plane.

In an embodiment, the inspection apparatus 10 may further include acommunication interface (not illustrated). The communication interfacemay perform wireless or wired communication between the inspectionapparatus 10 and the server, or between the inspection apparatus 10 andanother external apparatus. For example, the communication interface mayperform wireless communication in accordance with Long-Term Evolution(LTE), LTE-A (LTE Advance), Code Division Multiple Access (CDMA),Wideband CDMA (WCDMA), Wireless Broadband (WiBro), Wi-Fi, Bluetooth,Near Field Communication (NFC), Global Positioning System (GPS), GlobalNavigation Satellite System (GNSS), or the like. For example, thecommunication interface may perform wired communication in accordancewith Universal Serial Bus (USB), High Definition Multimedia Interface(HDMI), Recommended Standard 232 (RS-232), Plain Old Telephone Service(POTS), or the like. In an embodiment, the processor 110 may control thecommunication interface so as to acquire necessary information from theserver. The information acquired from the server may be stored in thememory 120. In an embodiment, the information acquired from the servermay include the above-described reference information or the like.

In an embodiment, the inspection apparatus 10 may further include aninput device (not illustrated). The input device may be a device thatreceives data input from the outside so as to transfer the data to atleast one component of the inspection apparatus 10. The input device mayinclude, for example, a mouse, a keyboard, and a touch pad.

In an embodiment, the inspection apparatus 10 may further include anoutput device (not illustrated). The output devices may visually providevarious data such as an inspection result and an operation state of theinspection apparatus 10 to the user. The output devices may include, forexample, a display, a projector, a hologram, and the like.

In an embodiment, the inspection apparatus 10 may include various typesof devices. The inspection apparatus 10 may include, for example, aportable communication device, a computer device, or a device accordingto one or more combinations of the above-described devices. Theinspection apparatus 10 of the present disclosure is not limited to theabove-described devices.

Various embodiments of the inspection apparatus 10 according to thepresent disclosure may be combined with one another. Respectiveembodiments may be combined according to the number of cases, and anembodiment of a combined inspection apparatus 10 also belongs to thescope of the present disclosure. In addition, the internal/externalcomponents of the inspection apparatus 10 according to theabove-described present disclosure may be added, changed, substituted,or deleted in accordance with embodiments. In addition, theinternal/external components of the above-described inspection apparatus10 may be implemented using hardware components.

FIG. 3 illustrates a process in which the structured lights are radiatedonto the object according to an embodiment of the present disclosure. Asdescribed above, for each of the plurality of structured lights, theoptical path may be adjusted such that each light beam corresponding toone phase of the one structured light is radiated over the entirety ofthe above-mentioned partial region of the object 3. The followingdescription will be made based on one structured light.

The structured-light source 130 may radiate a structured light havingone phase range. Optical paths 3010, 3020, and 3030 of light beamscorresponding to three arbitrary phases within the phase range areillustrated. Each light beam may be radiated to the surface of theobject 3 via the first diaphragm 160, the first beam splitter 150,and/or at least one lens. As described above, a light beam correspondingto one phase may be radiated to the entirety of the above-mentionedpartial region of the object 3. That is, the light beam 3010corresponding to one phase may be radiated so as to arrive at each pointof the partial region on the object 3. Light beams 3020 and 3030corresponding to different phases of the structured light may also beradiated to the object 3 in the same manner. Accordingly, at one pointof the partial region on the object 3, portions of all the light beamscorresponding to each phase of the phase range may be radiated. Forexample, in the illustrated embodiment, portions of all the light beams3010, 3020, and 3030 arrive at one point of the partial region on theobject 3, while other portions of all the light beams 3010, 3020, and3030 arrive at a different point of the partial region. Therefore, alight beam having an average light quantity of the structured lightcorresponding to the above-described phase range may be radiated overthe entirety of the partial region of the object 3.

A light radiated onto the partial region on the surface of the object 3is reflected to generate a reflected light, and the reflected light maybe input into the image sensor 140. The reflected light may be inputinto the image sensor 140 through the second diaphragm 170. As describedabove, only some of the reflected light may pass through the seconddiaphragm 170 when the surface of the object 3 is tilted with respect tothe reference plane (i.e., when the angle of the surface of the objectis not zero). That is, only some of the light passing through the firstdiaphragm 160 may pass through the second diaphragm 170. Some of thereflected light passing through the second diaphragm 170 may correspondto a partial phase range of the phase range of the structured lightradiated from the structured-light source 130. The average lightquantity of the light corresponding to this partial phase range may beconsequently captured by the image sensor 140.

In an illustrated embodiment (3040), the angle of the surface of theobject 3 may be zero degrees. In this case, most of the light thatcorresponds to each phase of the structured light concentrated into onepoint of the partial region on the surface of the object 3, may bereflected from the surface of the object 3 and then input into the imagesensor 140 through the second diaphragm 170. The light corresponding tothe phase interval denoted by A and A′ in the embodiment (3040) may bereflected from the surface of the object 3 and then input into the imagesensor 140 through the second diaphragm 170.

In an illustrated embodiment (3050), the object 3 may be tilted at anangle of 3 degrees with respect to the reference plane. In this case,only some of the light that corresponds to each phase of the structuredlight concentrated into one point of the partial region on the surfaceof the object 3, may be reflected from the surface of the object 3 andthen input into the image sensor 140 through the second diaphragm 170.Specifically, the region through which the first diaphragm 160 allowsthe structured light to pass may correspond to a section indicated by anillustrated straight line 3051. The region, which allows a lightstarting from one point on the surface of the object 3 to pass throughthe second diaphragm 170, may correspond to a section indicated by anillustrated straight line 3052. Accordingly, a light beam with theoptical path passing through both the first diaphragm 160 and the seconddiaphragm 170 may be a light beam having a phase that belongs to thephase interval indicated by A and A′ in the drawings. The light quantityof reflected light acquired by the image sensor 140 may be an averagelight quantity of the light beams corresponding to the phase intervalindicated by A and A′.

In an illustrated embodiment (3060), the object 3 may be tilted at anangle of 5 degrees with respect to the reference plane. In this case,most of the light that corresponds to each phase of the structured lightconcentrated into one point of the partial region on the surface of theobject 3, may be reflected from the surface of the object 3 and then maynot be able to pass through the second diaphragm 170. Accordingly, theimage sensor 140 may not be able to capture the reflected light. Theangle of the surface of the object 3 in each of the above-describedembodiments (3040, 3050, and 3060) may be an exemplary value selectedfor description.

That is, the light quantity input into the image sensor 140 through boththe first diaphragm 160 and the second diaphragm 170 may vary dependingon the angle of the surface of the object 3. The inspection apparatus 10may derive the angle of the surface of the object 3 using a change inthe light quantity of reflected light. Since the structured-light sourcesequentially radiates the plurality of structured lights, the operationdescribed above can be applied in the same manner to each of theplurality of structured lights.

FIG. 4 illustrates a process in which the reflected light passes throughthe second diaphragm according to an embodiment of the presentdisclosure. The illustrated embodiment may illustrate the case where thesurface of the object is tilted at a predetermined angle with respect tothe reference plane, as in the embodiment (3050) described above.

A structured light having one phase range may be radiated from thestructured-light source 130 and may be uniformly radiated onto thepartial region on the surface of the object 3. This may be performed asdescribed above regardless of the angle of the surface of the object.

Since the surface of the object is tilted, only some of the reflectedlight may be input into the image sensor 140 through the seconddiaphragm 170. Of the reflected light generated by the light beams 3010,3020, and 3030 incident on the partial region, only the portion of thereflected light traveling along the optical path within the rangeindicated by the thick solid lines may be input into the image sensor140 through the second diaphragm 170.

The portion of the reflected light which is input into the image sensor140 may be that which is obtained when light beams corresponding to apartial range of the phase range of the structured light are reflectedfrom the surface of the object. Consequently, the light quantity of thereflected light acquired by the image sensor 140 may be the averagelight quantity of the light beams corresponding to the above-describedpartial range of the structured light.

FIG. 5 illustrates a process in which the reflected light passes throughthe second diaphragm according to an embodiment of the presentdisclosure. In the illustrated embodiment, a part of the surface of theobject 3 may not be tilted with respect to the reference plane, and theother part may be tilted.

A light reflected from a point A of the surface of the object 3, whichis not tilted with respect to the reference plane, may be input into acorresponding point of the image sensor 140 through the second diaphragm170 as in the above-described embodiment 3040 (thick solid lines). Thecorresponding point of the image sensor 140 may receive the averagelight quantity of the structured light corresponding to theabove-described phase range radiated from the structured-light source130.

On the other hand, only a portion of light reflected from a point B ofthe surface of the object 3, which is tilted with respect to thereference plane, may be input into a corresponding point of the imagesensor 140 through the second diaphragm 170 as in the above-describedembodiment 3050 (thick dotted lines). The corresponding point of theimage sensor 140 may receive the average light quantity of only thelight beams of the structured light corresponding to the above-describedpartial range of the phase range radiated from the structured-lightsource 130.

A tilt value at each point of the partial region on the surface of theobject may be obtained using each of average light quantity values whichhave been input for each point (pixel) of the image sensor 140.

FIG. 6 illustrates the view of a plurality of structured lights in afirst diaphragm 160 radiated from the structured-light source 130according to an embodiment of the present disclosure. As describedabove, the structured-light source 130 may radiate a plurality ofstructured lights having one phase range, and each of the plurality ofstructured lights may be generated by being phase-shifted by apredetermined phase interval. For example, when the structured-lightsource 130 is implemented by a square LCoS, the LCoS may have 1280×1024pixels and of these, 1024×1024 pixels may generate a structured light.Depending on the phase range of each bucket, the light beams of thestructured light radiated by the point light sources of the LCoS mayhave different brightness distributions.

A pattern of one structured light may have a period. The plurality ofpoint light sources of the structured-light source 130 may vary thebrightnesses of light beams radiated from the plurality of point lightsources depending on the positions of the plurality of point lightsources, thereby making the structured lights have patterns depending onthe brightnesses. Assuming that the phase corresponding to one period is2π, the pattern of the structured light may become gradually brighterduring the interval from 0 to π/2, and the pattern of the structuredlight may become gradually darker during the interval from π/2 to 3*π/2,and the pattern of the structured light may become gradually brighteragain during the interval from 3*π/2 to 2π.

The phase range of the structured light to be irradiated may be setaccording to a designer's intention. In an embodiment, the phase rangemay be set so as not to be one period or a multiple of one period of thepattern. That is, the phase range may be set to a phase range other thanan integer multiple of the period of the structured light. At this time,the phase range may be set to a range other than the phase rangescorresponding to 0, 2π, 4π, . . . , and 2nπ. This is because, when astructured light having a phase range that is one period or a multipleof one period is used, the light beams corresponding to each phase ofthe structured light may cancel each other since a light correspondingto the average light quantity of the structured light is radiated to thepartial region on the object 3. Therefore, in order to prevent theaverage light quantity from being canceled to zero, the phase range maybe set so as not to be one period or a multiple of one period of thepattern. In one embodiment, periods of the plurality of structuredlights may be the same.

In an embodiment, the phase range may be set to be greater than thephase range corresponding to a half-period of the structured light andsmaller than the phase range corresponding to one period of thestructured light. In an embodiment, the phase range may be set to begreater than the phase range corresponding to (N+½) period of thestructured light (N is a natural number) and smaller than the phaserange corresponding to (N+1) period of the structured light. That is, arange obtained by adding a range that corresponds to a multiple of oneperiod to a range that is larger than a half-period and smaller than oneperiod may be set as the above-described phase range. The phase rangemay be set in this manner when it is necessary to increase the totallight quantity of the structured lights in order to facilitate themeasurement of the reflected lights.

One structured light corresponding to the above-mentioned phase rangemay be phase-shifted by a predetermined phase interval to form theplurality of structured lights. In an embodiment, the above-describedphase interval may be set to a value greater than zero and smaller thanπ. In an embodiment, the above-described phase interval may be set toπ/2. For example, the structured light corresponding to one phase rangemay be phase-shifted by π/2 to form a plurality of structured lights.

The plurality of structured lights may be referred to as four buckets,including a zeroth bucket, a first bucket, a second bucket and a thirdbucket, respectively. Each of the plurality of structured lights mayalso have a phase range corresponding to a predetermined phase range(e.g., α). Since the structured lights may be generated by thephase-shifting of one structured light, each of the structured lightsmay have a phase range from 0 to α, a phase range from π/2 to π/2+α, aphase range from π to π+α, and a phase range from 3*π/2 to 3*π/2+α ofone structured light, respectively. Each of the plurality of structuredlights generated in the above-described manner may be sequentiallyradiated to the object 3.

In the first diaphragm 160, the radiated structured light of each bucketat the structured-light source 130 may be displayed as shown in thedrawing (5020). The region of the first diaphragm 160 through which astructured light passes may be circular. Thus, of the structured lightsin the rectangular shape in the structured-light source 130, the lightbeams corresponding to the circular regions may be radiated to theobject 3.

According to the embodiment, the inspection apparatus according to thepresent disclosure may measure the angle of the surface of the objectusing only one structured light. It may be possible to derive the angleof the surface of the object by radiating one structured light to theobject and comparing the light quantity of the corresponding reflectedlight with the reference information. However, by measuring the angle ofthe surface of the object using a plurality of structured lights, it ispossible to reduce various measurement errors such as an error causeddue to the material of the surface of the object.

The total light quantity value of each of the structured lights in thestructured-light source 130 may be calculated using the followingequation.

I _(LCOS)=∫_(α) ^(β)(I ₀ +I ^(o) sin(φ))dφ  Equation 1

I^(o) may be a constant that determines the amplitude of a sinusoidalgraph of a pattern of a structured light, and I_(o) may be a constantthat determines the offset of the sinusoidal graph of the pattern. Thetotal light quantity value I_(LCoS) may be derived by integrating thestructured light at the structured-light source 130 in the phase range(from α to β).

FIG. 7 is a table illustrating the reference information according to anembodiment of the present disclosure. As described above, the referenceinformation may indicate a relation between the angle of the surface ofthe object 3 and the phase values of the plurality of reflected lights.The numerical values represented by the shown reference information areexemplary values, and the values of the reference information may varydepending on embodiments.

When one structured light is reflected from the above-mentioned partialregion of the object 3 and is captured by the image sensor 140, thelight quantity value I_(n) of the reflected light may be expressed as inthe following equation.

I _(n) =A+B cos(φ(x,y)−α(t))  [Equation 2]

A and B may correspond to I_(o) and I^(o) described above, respectively.Φ(x, y) may be a phase value of a reflected light beam reflected from apoint (x, y) of the partial region on the object 3. α(t) may representthe above-described phase shift amount.

The light quantity values I₁, I₂, I₃, and I₄ of the reflected lightsgenerated by reflecting each of the plurality of structured lights,which are generated by phase shifting by a phase interval of π/2, fromthe surface of the object 3 may be expressed by the following equation.That is, the light quantity of the reflected lights generated due to thestructured lights, which correspond to the four buckets, respectively,may be expressed as follows. Equation 3 may be obtained by applying thecorresponding values of α(t) to Equation 2, respectively, and thensummarizing Equation 2.

$\begin{matrix}{{I_{1} = {{A + {{{B\cos}(\varphi)}\mspace{14mu} {a(t)}}} = 0}}{I_{2} = {{A - {{{B\sin}(\varphi)}\mspace{14mu} {a(t)}}} = \frac{\pi}{2}}}{I_{3} = {{A - {{{B\cos}(\varphi)}\mspace{14mu} {a(t)}}} = \pi}}{I_{4} = {{A + {{{B\sin}(\varphi)}\mspace{14mu} {a(t)}}} = \frac{3\pi}{2}}}} & \left\lbrack {{Equation}\mspace{14mu} 3} \right\rbrack\end{matrix}$

As described above, the light quantity acquired by the image sensor 140may be the average light quantity of light beams corresponding to a partof the phase range of the radiated structured light. Depending on theangle of the surface of the object, a part of the phase range maychange, and the light quantity acquired by the image sensor 140 may alsochange. In this operation, even if the object is tilted at the sameangle, since the plurality of structured lights are phase-shifted, lightbeams corresponding to the above-mentioned part of the phase range maybe changed in configuration. That is, depending on which bucket is used,light beams corresponding to the above-mentioned part of the phase rangemay be varied, and thus the average light quantity value acquired by theimage sensor 140 may also be varied. The light quantities of thereflected lights of the buckets may be the above-described I₁, I₂, I₃,and I₄, respectively.

The light quantity values I₁, I₂, I₃, and I₄ of the respective reflectedlights are values that can be measured by the image sensor 140. A, B,and φ can be derived using the above-described four equations for I₁,I₂, I₃, and I₄. Since there are three unknowns, at least three equationsare required. Thus, measurements through three or more differentstructured lights may have to be performed at least three times. Bysummarizing Equation 3, the phase value φ of a reflected light may bederived as follows.

$\begin{matrix}{\varphi = {\tan^{- 1}\left( \frac{I_{4} - I_{2}}{I_{1} - I_{3}} \right)}} & \left\lbrack {{Equation}\mspace{14mu} 4} \right\rbrack\end{matrix}$

As illustrated in the drawing, the reference information may include thetilt angles of the object, the light quantity values I₁, I₂, I₃, and I₄of the reflected light for each bucket measured for each correspondingangle, and information on the phase values of the reflected lightsderived through the measured light quantity values. For example, whenthe tilt angle of the object is 1 degree, the light quantity values I₁,I₂, I₃, and I₄ of the reflected lights for respective measured bucketsmay be 239.50, 145.67, 132.41, and 226.34, respectively. The phase valuederived from these light quantity values may be 37.02 degrees. In anembodiment, the reference information may also include the values of Aand B described above.

The reference information may be stored in the memory 120. The relationbetween the phase values and the tilt angles of the object indicated bythe reference information may be put in a database and stored in thememory 120 through measurement and calculation.

The processor 110 may derive the angle of the surface of the object 3 byderiving the phase values of the reflected lights based on the lightquantity values and comparing the derived phase values of the reflectedlights and the reference information acquired from the memory 120.

FIG. 8 shows the directions of patterns of structured lights accordingto an embodiment of the present disclosure. According to an embodiment,the structured-light source 130 may be implemented by a rectangularLCoS. Depending on the phase range of each bucket, the light beamsradiated by the point light sources of the LCoS may have differentbrightness distributions, and thus a pattern may be formed.

When the axis corresponding to one side of the rectangular LCoS is the Xaxis and the axis, which corresponds to another side and isperpendicular to the X axis, is the Y axis, the pattern of thestructured lights may be formed in the X-axis direction or the Y-axisdirection. In an embodiment, each of the plurality of structured lightsmay have a pattern in the X-axis direction or in the Y-axis directionthat is perpendicular to the X axis. In an embodiment, the patterndirections of the structured lights may be set differently for eachbucket. In an embodiment, by using a plurality of patterns formed in therespective axial directions, it is possible to reduce errors in theangle measurement of the surface of an object.

FIG. 9 illustrates the configuration of the structured-light source 130according to an embodiment of the present disclosure. Theabove-described patterns of the structured lights may be formed throughvarious methods. According to an embodiment, the patterns of thestructured lights may be formed through a digital method or through ananalog method. The digital method may be a liquid crystal transmissionmethod using a Liquid Crystal Display (LCD), a liquid crystal reflectionmethod using Liquid Crystal on Silicon (LCoS), a mirror reflection usinga Digital Micromirror Device (DMD), or a mirror reflection method usingDigital Light Processing (DLP). In the analog method, a pattern may beformed using patterns such as a periodic pattern, a gradient pattern,and a lattice pattern.

The structured-light source 130 may also be implemented in variousmanners depending on a method of forming a pattern of structured light.As an example, an embodiment of the structured-light source 130configured to form a pattern of structured light using LCoS will bedescribed below.

In an embodiment using LCoS, the structured-light source 130 may includea light source 131, a diffusion plate 132, a second beam splitter 133,and/or a pattern generator 134. In an embodiment, at least one of thesecomponents of the structured-light source 130 may be omitted, or anothercomponent may be added to the structured-light source 130. Here, thepattern generator 134 may be implemented with the LCoS described above.

The light source 131 is able to radiate an illumination light. Theillumination light is light having no pattern, and may include ahorizontally polarized light and/or a vertically polarized light. Thehorizontally polarized light is a polarized light in which the vibrationdirection is parallel to the radiation direction, and may be referred toas P-wave or a first polarized light. The vertically polarized light isa polarized light in which the vibration direction is perpendicular tothe radiation direction, and may be referred to as S-wave or a secondpolarized light. The light source 131 may be implemented by an LED. Thediffusion plate 132 is able to diffuse the illumination light from thelight source 131.

The second beam splitter 133 may adjust the optical path by receivingthe illumination light from the diffuser plate 132. The second beamsplitter 133 may transmit the first polarized light and reflect thesecond polarized light. Specifically, the second beam splitter 133 maytransmit the first polarized light of the illumination light (1020) soas to direct the first polarized light to the pattern generator 134.Further, the second beam splitter 133 may reflect the second polarizedlight of the illumination light (1010). The reflected second polarizedlight (1010) may not be used in generating a structured light. Thesecond beam splitter 133 may be implemented by a Polarizing BeamSplitter (PBS).

The pattern generator 134 may receive the first polarized light of theirradiated light and reflect a part of the received first polarizedlight as the first polarized light, and may convert another part of thereceived first polarized light into a second polarized light and reflectthe second polarized light. The pattern generator 134 may have aplurality of elements. When an element is turned off, the correspondingelement may reflect the received first polarized light (1020) as it isin the form of a first polarized light (not illustrated). When anelement is turned on, the corresponding element may convert the receivedfirst polarized light (1020) into a second polarized light (1030), andreflect the converted second polarized light (1030). By causing eachelement to be turned on/off, the pattern generator 134 may generate apattern.

The second beam splitter 133 may transmit the first polarized light (notillustrated), reflected and delivered to the second beam splitter 133,as it is. This first polarized light (not illustrated) may not form astructured light (1040). The part corresponding to the unused firstpolarized light may correspond to the dark portion of the structuredlight (1040). The second beam splitter 133 may reflect the secondpolarized light (1030) reflected and delivered to the second beamsplitter 133. The second polarized light (1030) may be used to form abright portion of the structured light (1040). The generated structuredlight may be delivered to the first beam splitter 150 described above.The structured light generated according to the embodiment may bedelivered to the first beam splitter 150 through an additional mirror orthe like.

FIG. 10 is a flowchart illustrating an embodiment of an inspectionmethod that may be performed using an inspection apparatus 10 accordingto the present disclosure. Although respective steps of the method oralgorithm according to the present disclosure are illustrated in asequential order in the illustrated flow chart, the respective steps maybe performed in an order in which the steps may optionally be combinedby the present disclosure, in addition to being performed sequentially.The description with reference to this flowchart is not intended topreclude a change or modification to the method or algorithm, and doesnot mean that any step is necessary or desirable. In an embodiment, atleast some of the steps may be performed in parallel, repetitively, orheuristically. In an embodiment, at least some of the steps may beomitted, or other steps may be added.

The inspection apparatus 10 according to the present disclosure mayperform an inspection method according to various embodiments of thepresent disclosure in measuring the tilt angle of the object 3 withrespect to the reference plane. An inspection method according to anembodiment of the present disclosure may include: sequentially radiatingeach of a plurality of structured lights having one phase range (S100);adjusting optical paths of light beams corresponding to phases of thephase range (S200); capturing a plurality of reflected lights generatedby the plurality of structured lights being reflected from the partialregion (S300); acquiring a light quantity value of each of the pluralityof reflected lights (S400); and deriving the angle of the surface of theobject based on the light quantity value (S500).

In step S100, the structured-light source 130 of the inspectionapparatus 10 may sequentially radiate a plurality of structured lightshaving one phase range. In step S200, the at least one lens of theinspection apparatus 10 may adjust the optical path of each of theplurality of structured lights. Specifically, the at least one lens mayadjust the optical paths of light beams corresponding to phases of thephase range such that a light beam corresponding to one phase of theabove-mentioned predetermined phase range arrives at each point of thepartial region on the surface of the object 3. Similarly, the at leastone lens may, for each of the plurality of structured lights, adjust theoptical path of a light beam corresponding to each of the phases of theabove-mentioned phase range.

In step S300, the image sensor 140 of the inspection apparatus 10 maycapture a plurality of reflected lights generated by the plurality ofstructured lights being reflected from the above-described partialregion of the object 3. In step S400, the processor 110 of theinspection apparatus 10 may acquire a light quantity value for each ofthe plurality of reflected lights from the image sensor 140. In stepS500, the processor 110 may derive the angle of the surface of theobject 3 based on the acquired light quantity value.

In an embodiment, step S500 of deriving the angle of the surface of theobject based on the light quantity value may include deriving, by theprocessor 110, the phase value of each of the plurality of reflectedlights based on the light quantity value, and deriving the angle of thesurface of the object based on the derived phase value and the referenceinformation. The reference information is as described above.

In an embodiment, the phase range may be set to a value other than aninteger multiple of the period of the structured lights. In oneembodiment, periods of the plurality of structured lights may be thesame. In an embodiment, the above-described phase range may be set to begreater than the phase range corresponding to (N+½) period of thestructured lights and smaller than the phase range corresponding to(N+1) period of the structured lights. N may be a natural number.

In an embodiment, the light quantity value of a reflected light may bedetermined based on a light quantity value of each of the plurality ofreflected lights passing through the second diaphragm 170 and beingcaptured by the image sensor 140. Each of the plurality of reflectedlights are generated by the plurality of structured lights from thestructured-light source 130, passing through the first diaphragm 160 andbeing reflected from the surface of the object 3. That is, as describedabove, the structured lights, radiated from the structured-light source130 may generate the reflected lights by passing through the firstdiaphragm 160 and by being reflected from the surface of the object 3. Apart of the reflected light passes through the second diaphragm 170. Thelight quantity of the reflected light passing through the seconddiaphragm 170 may vary depending on the angle of the surface of theobject 3.

In an embodiment, a light beam having a light quantity corresponding toan average light quantity of each of the plurality of structured lightscorresponding to the above-described phase range may arrive at eachpoint of the above-described partial region on the surface of the object3.

In an embodiment, each of the plurality of structured lights may begenerated by phase-shifting one structured light by a predeterminedphase interval.

Various embodiments of the present disclosure may be implemented assoftware in a machine-readable storage medium. The software may besoftware for implementing various embodiments of the present disclosuredescribed above. The software may be inferred from various embodimentsof the present disclosure by programmers of the technical field to whichthis disclosure belongs. For example, the software may be a programincluding machine-readable commands (e.g., codes or code segments). Themachine is an apparatus operable according to an instruction called froma storage medium, and may be, for example, a computer. In an embodiment,the machine may be the inspection apparatus 10 according to embodimentsof the present disclosure. In an embodiment, a processor of the machinemay execute the called commands so as to cause the components of themachine to perform functions corresponding to the commands. In anembodiment, the processor may be the processor 110 according toembodiments of the present disclosure. The term “storage medium” maymean all kinds of recording mediums, where machine-readable data isstored. The storage medium may include, for example, ROM, RAM, CD-ROM,magnetic tape, floppy disk, optical data storage, and the like. In anembodiment, the storage medium may be the memory 120. In an embodiment,the storage medium may be implemented in the form of being distributedon a networked computer systems or the like. The software may bedistributed and stored in computer systems or the like so as to beexecuted. The storage medium may be a non-transitory storage medium. Theterm “non-transitory storage medium” means a tangible medium regardlessof whether data is stored therein semi-permanently or temporarily, anddoes not include a signal propagated in a transitory manner.

Although the technical idea of the present disclosure has been describedabove by way of various embodiments, the technical scope of the presentdisclosure covers various substitutions, modifications, and changes thatcan be made by a person ordinarily skilled in the technical field towhich the present disclosure belongs. It should also be understood thatsuch substitutions, modifications and changes are intended to fallwithin the scope of the present disclosure that is defined in theaccompanying claims.

What is claimed is:
 1. An apparatus comprising: a structured-lightsource configured to sequentially radiate a plurality of structuredlights having a predetermined phase range; at least one lens configuredto adjust optical paths of the plurality of structured lights such thateach of the plurality of structured lights is uniformly radiated to aregion on an object; an image sensor configured to capture a pluralityof reflected lights generated by the plurality of structured lightsreflected from the region; a memory that stores reference information onan inclination of the region; and a processor configured to: acquirelight quantity values of the plurality of reflected lights from theimage sensor; and derive an angle of the region with respect to areference plane based on the light quantity values and the referenceinformation.
 2. The apparatus of claim 1, wherein the referenceinformation indicates a relation between the angle of the region and thelight quantity values of the plurality of reflected lights.
 3. Theapparatus of claim 1, wherein each of the plurality of structured lightsincludes a plurality of light beams, each of which corresponds to aphase of the phase range, and wherein the at least one lens is furtherconfigured to adjust optical paths of the plurality of light beams ofeach of the plurality of structured lights.
 4. The apparatus of claim 1,wherein the phase range is greater than a half-period of the pluralityof structured lights and smaller than a period of the plurality ofstructured lights.
 5. The apparatus of claim 1, wherein the plurality ofstructured lights are generated by phase-shifting one structured lightby a predetermined phase interval.
 6. A method, comprising: sequentiallyradiating, by a structured-light source, a plurality of structuredlights having a predetermined phase range; adjusting, by at least onelens, optical paths of the plurality of structured lights such that eachof the plurality of structured lights is uniformly radiated to a regionon an object; capturing, by an image sensor, a plurality of reflectedlights generated by the plurality of structured lights reflected fromthe region; acquiring, by a processor, light quantity values of theplurality of reflected lights from the image sensor; and deriving, bythe processor, an angle of the region with respect to a reference planebased on the light quantity values and reference information on aninclination of the region stored in a memory.
 7. The method of claim 6,wherein the reference information indicates a relation between the angleof the region and the light quantity values of the plurality ofreflected lights.
 8. The method of claim 6, wherein each of theplurality of structured lights includes a plurality of light beams, eachof which corresponds to a phase of the phase range, and wherein theadjusting optical paths of the plurality of structured lights includesadjusting optical paths of the plurality of light beams of each of theplurality of structured lights.
 9. The method of claim 6, wherein thephase range is greater than a half-period of the plurality of structuredlights and smaller than a period of the plurality of structured lights.10. The method of claim 6, wherein the plurality of structured lightsare generated by phase-shifting one structured light by a predeterminedphase interval.